But there is still a huge need for classical projects: i.e. projects to which observations are manually added, or added by virtue of observation fields that are required. To my mind these are "tagged" projects. (in iNat logic one traditionally "added observations to projects", but for similar projects on iSpot we added tags and created projects to filter on the tags - the net effect is the same, a lookup table of project-tag and observation, that can be used as a filter - either alone or with other filters).
The addition of a project-tag filter to the new projects will make the "traditional" projects into "collection type" projects too, while preserving the Project Icons on the observations.
((the additional functionality of defining observation fields from within a project is an extremely useful feature.))

A nitpick: is the central filter a Location filter (using google places) or a Place filter (using user-created iNat polygons) or both? It would help if the terminology was standardized with the observations pages and its filters.

No coordinates and you have other obs from the same day and all those obs from that day HAVE TIMES appending ?interpolate_coordinates=true to the edit observation URL (the URL you’re at when you’re editing an obs, e.g. https://www.inaturlaist.org/observations/edit?interpolate_coordinates=true) will fill in coordinates based on a time-weighted average of the nearest observations in time.

A nitpick: is the central filter a Location filter (using google places) or a Place filter (using user-created iNat polygons) or both? It would help if the terminology was standardized with the observations pages and its filters.